The aim of this study is to determine the effects of ocean depth on tsunami amplitudes used in source models for use in linear shallow-water wave theory. To determine the effects, 19 ocean depths ranging from 200-2000 m are studied. The results show that it is possible to establish a series-type exploration function to define the depth-amplitude effects. This function with the unknown coefficients related to ruptures of the ocean floor involves the normalized maximum tsunami amplitude. Results obtained from this series-function give good approximations for four or more terms in the series. Two basic source models are considered. Numerical examples are presented. (C) 2003 Elsevier Ltd. All rights reserved.